1. Field of the Invention
The invention relates generally to the cellular monitoring of protein expression and processing.
2. Background Information
The elucidation of the human genome and that of other species has greatly accelerated with the interest in proteomics, that is, the study of naturally occurring proteins and their intra- and extracellular interactions and activities. The ability to determine the status of a protein in a cell has far ranging opportunities in understanding the intracellular pathways, the intracellular movement of proteins into different compartments, the regulation of transcription and expression, the regulation of protein content and protein modification, and the like. Not only will this provide greater insight into how a cell operates, but it also allows for the determination of when a cell is aberrant or diseased. In addition, one can determine the effect of changes in the environment of the cell on the cellular function, as evidenced by changes in protein profiles, modification of proteins and transport of proteins.
Various approaches have been used to study protein-protein interactions, particularly using yeast as a host. While this can provide information concerning whether two proteins will interact, it gives no information about what happens in a native cell. The use of yeast as a host may also provide information about compounds that interfere with the interaction, but in an environment substantially different from the mammalian natural environment where the interaction may occur.
Other techniques have involved tagging a protein with a peptide fluorescer, e.g., green fluorescent protein, where degradation of the fusion protein can be followed by the loss of the fluorescence. This has many disadvantages in requiring a very large tag that may interfere with the folding of the native protein, its binding to other proteins, its susceptibility to degradation and its overall regulatory activity.
In studying the effect of drugs, both as to efficacy and differences in individual responses, it would be helpful to understand the differences in the individual hosts that result in the different responses. In understanding diseased states, it would be advantageous to be able to compare the changes in protein activity as a result of the cellular diseased state. By providing the capability to monitor changes in one or more proteins, therapeutic, diagnostic and scientific information can be developed.